Rotatable eccentric arrangement

Abstract

The present invention relates to a rotatable eccentric element for continuous adjustment of vibration amplitude, for use in, for example, the roll in vibrating rollers. In particular, the invention relates to a rotatable eccentric arrangement adapted for stepless adjustment of vibration amplitude, comprising a rotatable shaft ( 1 ) with an eccentric weight ( 2 ) arranged in a fixed manner thereon and a movable weight ( 5 ) which is pivotable relative to the fixed weight between a position with maximum amplitude and a position with minimum amplitude for changing the vibration amplitude of the arrangement. The invention is characterized in that the pivoting axis for the pivoting of the movable eccentric weight ( 5 ) is displaced from the axis of rotation of the shaft ( 1 ) and at least to an extent towards the centre of gravity of the fixed weight ( 2 ).

What is claimed is:  
     
       1. A rotatable eccentric arrangement adapted for stepless adjustment of vibration amplitude, comprising a rotatable shaft with at least one fixed eccentric weight arranged in a fixed manner thereon and at least one movable eccentric weight which is pivotable relative to the fixed weight between a position with minimum amplitude and a position with maximum amplitude for changing the vibration amplitude of the arrangement, the movable eccentric weight being restrained in its motion relative to the fixed eccentric weight to less than about one hundred eighty degrees of rotation and characterized in that a pivoting axis for the pivoting of the movable eccentric weight is displaced from the axis of rotation of the shaft towards the center of gravity of the fixed weight and that the movable weight is adapted so as to be automatically pivoted toward the position with maximum amplitude when a vibrational frequency decreases and towards the position with minimum amplitude when the vibrational frequency increases and in that a third weight is movably arranged and adapted such that the centrifugal force during rotation of the eccentric arrangement causes the third weight to exert a force against the movable weight so as to guide the movable weight from the position with maximum amplitude toward the position with minimum amplitude. 
     
     
       2. Eccentric arrangement according to patent  claim 1 , characterized in that the movable eccentric weight is adapted so as to be automatically pivoted so that centrifugal force which is exerted against bearings, in which the shaft is rotatably mounted, is kept essentially constant. 
     
     
       3. Eccentric arrangement according to  claim 1 , characterized in that a retaining means is adapted to lock the movable eccentric weight in the position with minimum amplitude at the start of rotation, which retaining means is adapted so as to be released at a given threshold frequency. 
     
     
       4. Eccentric arrangement according to  claim 1 , characterized in that the movable weight has a curved surface, and in that the third weight has a part bearing against the curved surface, the third weight being adapted in such a manner that the centrifugal force during rotation of the eccentric arrangement causes the bearing part to exert a force against he curved surface, and the surface being such that the force with which the third weight bears against the movable weight acts so as to guide the movable weight from the position with maximum amplitude toward the position with minimum amplitude. 
     
     
       5. Eccentric arrangement according to patent  claim 4 , characterized in that the curved surface has a continuously decreasing distance to the axis of rotation from a bearing point of the third weight in the position with maximum amplitude to the bearing point at minimum amplitude. 
     
     
       6. Eccentric arrangement according to patent  claim 4 , characterized in that the curved surface has a continuously increasing distance to the axis of rotation from a bearing point of the third weight in the position with maximum amplitude to the bearing point at minimum amplitude. 
     
     
       7. Eccentric arrangement according to  claim 4 , characterized in that a spring is arranged so that it exerts a first force, so as to partially counteract a second force with which the bearing part bears against the curved surface. 
     
     
       8. Eccentric arrangement according to  claim 1 , characterized in that a retaining means is adapted to lock the movable eccentric weight in the position with minimum amplitude at the start of rotation, which retaining means is adapted so as to be released at a given threshold frequency. 
     
     
       9. Eccentric arrangement according to  claim 2 , characterized in that a retaining means is adapted to lock the movable eccentric weight in the position with minimum amplitude at the start of rotation, which retaining means is adapted so as to be released at a given threshold frequency. 
     
     
       10. Eccentric arrangement according to  claim 1 , characterized in that the movable weight has a curved surface, and in that a third weight is movably arranged and has a part bearing against the curved surface, the third weight being adapted in such a manner that the centrifugal force during rotation of the eccentric arrangement causes the bearing part to exert a force against he curved surface, and the curvature of the surface being such that the force with which the third weight bears against the movable weight acts so as to guide the movable weight from the position with maximum amplitude towards the position with minimum amplitude. 
     
     
       11. Eccentric arrangement according to  claim 2 , characterized in that the movable weight has a curved surface, and in that the third weight is movably arranged and has a part bearing against the curved surface, the third weight being adapted in such a manner that the centrifugal force during rotation of the eccentric arrangement causes the bearing part to exert a force against he curved surface, and the curvature of the surface being such that the force with which the third weight bears against the movable weight acts so as to guide the movable weight from the position with maximum amplitude towards the position with minimum amplitude. 
     
     
       12. Eccentric arrangement according to  claim 3 , characterized in that the movable weight has a curved surface, and in that the third weight is movably arranged and has a part bearing against the curved surface, the third weight being adapted in such a manner that the centrifugal force during rotation of the eccentric arrangement causes the bearing part to exert a force against he curved surface, and the curvature of the surface being such that the force with which the third weight bears against the movable weight acts so as to guide the movable weight from the position with maximum amplitude towards the position with minimum amplitude. 
     
     
       13. Eccentric arrangement according to  claim 5 , characterized in that a spring is arranged so that it exerts a first force, so as to partially counteract a second force with which the bearing part bears against the curved surface. 
     
     
       14. Eccentric arrangement according to  claim 6 , characterized in that a spring is arranged so that it exerts a first force, so as to partially counteract a second force with which the bearing part bears against the curved surface.